Vízügyi Közlemények, 1986 (68. évfolyam)

2. füzet - Fejér László: A vízsebességmérések fejlődése Magyarországon a vízrajzi osztály megalakulása előtt

280 Fejér László rovására végezték a vízrajzi felvételeket, s jellemző a helyzetre, hogy az igen fontos nagyvízi méréseket éppen az árvizek elleni védekezés munkái miatt nem tudták megejteni. A lassan tarthatatlanná váló helyzetben a megoldás nem késett már sokáig. Péch József gondos előkészítő munkájának eredményeképpen 1886. május 1-én a Baross Gábor vezette Közmunka- és Közlekedésügyi Minisztériumban megalakult a Vízrajzi Osztály, amellyel a hazai vízrajzi munkálatok történetében egy újabb szakasz kezdődött el. * * + The development of flow velocity measurements in Hungary before the organization of the Hydrographical Service by L. FEJÉR, С. E. According to available data it was L. F. Marsigli who measured first flow velocities (in the 1700's) along the Danube with a quadrant in the cross-sections of Pétervárad and Zsablya. Marsigli was, however, not interested in practical aspects, he was governed by scientific endeavour. Economic progress in the second half of the 18th century has initiated the regulation of the Danube and Tisza rivers with their tributaries. This was preceded by hydrographie surveys on the same rivers. At the university of Budapest a state-sponsored education of engineers began in 1782 and one of the main tasks of these graduated engineers was the execution of such surveys. The world-known scholars of the institute of engineering of the university Profs. Hadaly, Horváth and Rausch were theoreticians in hydrometry but despite of this Mr. Hadaly was the first to publish the results of a flow velocity measurements in 1783 (Fig. 2). In the first decades of the 19th century flow velocities were measured by buoys also in Hungary, or they were calculated by aid of the Chézy-equation based on the parameters of the particular river-bed. The first director of hydrographie surveys over the Danube, M. Huszár was first to apply the Woltman-rotor in our century (just around 1820). During successive point measurements he observed that the discharges had fluctuated according to the immediate slope of the water surface. Serial measurements were executed in the years of 1835-36 with an instrument that can be seen in Fig. 3. After completion of the surveys over the Danube (1845) an important period has been closed down in the history of Hungarian hydrometry. Afterwards, the accumulated experiences were processed and published. By use of the data of point measurements at the cross-section of Buda on the Danube (1938) an invention of P. Vásárhelyi was published (1845) in which he could prove that vertical velocity curves could be described by aid of a parabole with a horizontal axis. The problems about the laws of water motion were introduced in the curriculum of the Institutum. Based on lectures of Prof. J. Petzelt the first textbook dealing with hydraulic construction was edited in Hungarian language in 1847 where several chapters were devoted to the problems of hydrometry. It was Petzelt's merit that regular hydraulic exercises were held for engineering students. The extended river regulation projects initiated around the middle of the 19th century in the Tisza-Valley were not as successful, in every case, as this was expected by those interested in this large-scale undertaking. Beyond his scientific interest, Prof. I. Horváth (Fig. 5) wanted to use these experiences at the regulation work of the Danube. He initiated study-measurements on occasion of an icy flood on the Danube in 1876. To detect the nature and pattern of vertical velocity distributions the integrating method introduced by Gy. Révy and the pontoon by pontoon method were used interchanged. His equipment for velocity measurement was prepared by himself. The basis of it was a rotating rotor supplied by an electric signalling system produced by Amsler-Laffon. Smaller structural modifications were perfomed by the producer according to the demands of